Apparatus for the manufacture of mercury sulphate



Nov. 16, 1937. R. J. BAIRD 2,099,290

APlfARATUS FOR THE MANUFACTURE OF MERCURY SULBHATE Original Filed Feb 4,1952 EmldJBaint,

INVENTOR:

fi mal c ATT NEY.

Patented Nov. 16, 1937 UNITED STATES PATENT OFFICE PPARATUS FOR THEMANUFACTURE OF MERCURY SULPHATE Ronald J. Baird, Passaic, N. J.,assignor to A. 0. Smith Corporation, Milwaukee, Wis., a corporation ofNew York Original application February 4, 1932, Serial No.

590,918. Divided and this application her 6, 1935, Serial No. 53,229 v 6Claims.

substance containing sulphate ions and a soluble substance containing ananion which forms a water soluble mercury salt. The bath is electrolyzedin my new apparatus and an insoluble sulphate of mercury is produced.

The following specific embodiment is illustrative of the invention andrepresents'one mode in which the invention can be carried out but it isto be understood that the invention is not limited thereto and thatmodifications thereof may be made without departing from the invention.

Metallic mercury is placed in a water solution containing about 2% ofsulphuric acid and about 10% of sodium nitrate, by weight. The solutionis electrolyzed in my new apparatus by making the mercury an anode andpassing a direct current of about 0.5 of an ampere per square decimeterof mercury surface through the solution. Crystals of insoluble mercuroussulphate are formed directly above the metallic mercury. These crystalsare removed from the solution and ar ready for use as a catalyst.

If it isdesirable to remove traces of electrolyte which may be presenton the crystals they can be removed by washing the crystals in water anddrying them. The washed product is substantially pure crystallinemercurous sulphate.

The sodium nitrate appears to act as a catalyst in the preparation ofthe sulphate and it does not have to be replenished as the process iscontinued. Mercury, sulphuric acid and water are replenished as they areconsumed or evaporated so as to substantially preserve the above statedproportions of the electrolyte and to provide metallic mercury.

The electrolysis may be explained on the following hypothesis but it isto be understood that the invention is not limited thereto. It appearsthat the solution becomes dissociated yielding Na+ as a cation and NO:as an anion, The NO;

Decemanion combines with the Hg of the anode and forms a solublemercurous nitrate,

which reacts with the sulphuric acid and forms an insoluble mercuroussulphate,

The Na cation combines with water which is prcs- I ent in the solutionand forms sodium hydroxide,

2Na+2HzO2NaOH+Hz (3) which hydroxide unites with the nitric acid formedsimultaneously with the mercurous sulphate in equation (2) and reformsthe sodium nitrate which was originally in the solution,

The mercurous sulphate crystals do not form on the immediate surface ofthe mercury so as to produce a crust or a sludge. They are formed in thesolution above the surface of the mercury and they may be readilyremoved and collected out of contact therewith.

The size and density of the crystals formed is of prime importance inthe use of mercurous sulphate as a catalyst. The sulphate is especiallyintended for use as a catalyst in a bath which is subject to foaming.When the catalyst used in such a bath is in a fine or fiocculentcondition, considerable entrainment losses thereof in the foam have beenfound to take place and. when the catalyst is in a coarse andcrystalline or dense condition, the entrainment losses of the catalysthave been found to'be'small or negligible. It has been found that theabove mentioned solution.

containing about 2% of sulphuric acid and about 10% of sodium nitrateand carryinga current of about 0.5 of an ampere per square decimeteryields dense crystals of suflicient size to be particularly adapted foruse as a catalyst in a foaming bath with substantially negligibleentrainment losses. The use of a larger percentage of the sulphuric acidgave smaller crystal sizes. A current density of about 1.0 ampere persquare decimeter with the 2% sulphate solution gave small and less densecrystals of the mercurous sulphate.

By varying the concentration of the S04 and the N03 ions and by varyingthe ratio of the S04 ions to the NO: ions, different sized crystals ofthe mercurous sulphate are formed.

Atmospheric temperatures and pressures are used.

Qther compolmds may be employed in the elecwill not dissolve themercurous sulphate in the electrolyte. Salts which may be used are, forexample, the nitrates, chlorates, or acetates of .sodium, potassium,magnesium, aluminum or ammonium. Soluble sulphates which may be usedare, for example, sodium, ammonium, magnesium, or potassium sulphates.

The single figure in the accompanying drawing is a cross-sectional viewin elevation of my new apparatus with which the present invention isprimarily concerned. r

In the drawing, the numeral I refers to a cylindrical container made ofan acid resistant material, such as glass, lead, rubber, enameled steel,wood or concrete. The container is provided with a conically shapedbottom 2 which terminates in a flanged portion 3 and forms an opening 4through the bottom of the container. {Lflexible tubing 5 is fitted overthe flanged portion 3 and a clip 6 is provided to pinch the sides of thetubing 5 together so as to close communication through the opening 4 tothe outside. Within the container and positioned at intervals around theconical portion 2 are a plurality of bosses or supports I upon whichthere is supported a shallow vessel 8 composed of acid resistantmaterial which may also be non-conductive such as glass, rubber or wood.Resilient and insulating cushions 9 may be positioned on the supportingsurfaces of bosses I to improve the insulation of non-conductive vessel8 from the tank I or to provide insulation when a conductiveacidresistant vessel is used. A tubular conduit I0 composed ofinsulating material extends through the side wall II of the vessel 8 andan electrical conductor I2, which is passed through the conduit I0,terminates in a projection I3 within the vessel 8. The vessel is filledwith metallic mercury I4 and electrical connection is made between themercury and the proiection I3. The conductor I2 is adapted to beconnected to a positive terminal I! of a source of direct current.

An agitator or sweep I8. is secured to the lower end of shaft I I whichis journaled in a bearing I8.

sweep I8 is positioned in. a horizontal plane above and adjacent to thesurface of the mercury I4.

Between the sweep I6 and the top of the container I a perforated disk 2|of a conductive ma- 'terial, such as copper or lead, is supported onbrackets 22 which are secured to and depend from the top of thecontainer I. The perforations permit escape of hydrogen that is formedduring the process. Insulation 23 is placed between the container I andthe brackets 22. The disk 2i is adapted to be connected to a negativeterminal 24 ofthe source of direct current. J

The various detailed parts of the apparatus are made of materials whichare suitableto the function they are to serve and to the nature of thesurrounding medium. The particular material to be used for the variousparts will readily suggest itself to the chemist. v

The water solution containing about 2% sulphuric acid and about 10%sodium nitrate is poured into the vessel I so that the disk 2| will besubmerged. The electric circuit is closed and the agitator I6 is rotatedto sweep the mercurous crystals over the edge of the vessel 8. Themercurous crystals have a high specific gravity and they collect in thebottom of the container I from which they may be withdrawn by releasingthe clip 6 on the flexible hose 5. About 2 volts are applied to theelectrodes I4 and 2I which are spaced about one and one-half inchesapart and a current of about 0.5 of an ampere per square decimeter ispassed through the electrolyte.

The invention provides .a novel apparatus wherein a method of making acompound of mercury may be carried out in a simple and direct manner. Nosludge or crust is formed on the surface of the mercury, and, therefore,there is no obstruction to continued operation of the process and noloss of metallic mercury due to entrainment thereof in the crystalswhich are removed.

Having thusv described my invention, what I declare is new and desire tosecure by Letters Patent of the United'States is:

1. An apparatus for the preparation of mercury salts comprising acontainer having sidewalls and a funnel-shaped bottom provided withclosure means adapted to be opened for removing a portion of the saltformed, a shallow, non-conductive,'acid-resistant vessel containingmercury as an anode supported'near, but above the container bottom, andspaced from the container sidewalls, an insulated electrical conductorleading into the shallow vessel, an agitator positioned in closeproximity to the shallow vessel for removing mercury salts from thevicinity thereof, a cathode positioned in the container, and a secondelectrical conductor leading to the oathode.

2. An apparatus for the preparation of a mercury salt comprising acontainer provided with walls and a bottom which terminates in closuremeans adapted to be opened for removing at least a portion of themercury salt, a plurality of supports carried by the container, anon-conductive, acid-resistant vessel containing mercury positioned uponthe supports so that the vessel is spaced from the container walls andbottom, an insulated electrical conductor leading into the vessel, sweepmeans positionedabove the vessel for sweeping the mercury clear ofmercury salt, a cathode plate positioned in close proximity to thevessel, and a second electrical conductor leading into the container tothe cathode'plate'.

3. An apparatus for the preparation of a crystalline mercury saltcomprising a container provided with walls and a bottom which terminatesof a mercury salt comprising a container provided with sidewalls and abottom which terminates in closure means whereby at leasts. portion ofthe container contents may be removed therefrom, a non-conductive,acid-resistant vessel containing mercury supported in the container butspaced from the bottom and sidewalls thereof, an insulated electricalconductor leading to the vessel, a mechanical sweep positioned abovepositioned above the mechanical sweep and supported by brackets .securedto and depending from the top of the container, and an electricalconductor leading into the container to the cathode.

5. An apparatus for the'preparation of a metal salt comprising a glasscontainer having side- 7 walls and a funnel-shaped bottom provided withclosure means adapted to be opened for removing a portion of the metalsalt formed, a nonconductive, acid-resistant vessel for an anodesupported in the container and spaced from the container bottom and thecontainer sidewalls, an insulated electrical conductor leading into thevessel, an agitator positioned in close proximity tom and the containersidewalls,

to the vessel for removing metal salt. from the vicinity thereof, and asecond electrical conductor leading into the container.

6. An apparatus for the preparation of a metalsalt comprising acontainer having sidewalls and a bottom-provided with closure meansadapted to be opened for removing metal salt, a shallow, non-conductive,in the container spaced from the container botan insulated electricalconductor leading into the shallow vese sel, an agitator positioned inclose proximity to the shallow vessel for removing metal salt from thevicinity thereof, and a second electrical conductor leading into thecontainer.

- RONALD J. BAIRD.

acid-resistant vessel supported

